Ernest p



(No Model.)

B. P. CLARK.

SAFETY DEVICE FOR DYNAMOS.

No. 426,109. Patented Apr. 22, 1890'.

, INVENTOI? frames Clay) BY A TTORNEY.

nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn c4 UNITED STATES PATENT OFFICE.

ERNEST P. CLARK, OF NEXV YORK, N. Y., ASSIGNOR TO THE CLARK ELECTRIC COMPANY, OF SAME PLACE.

SAFETY DEVICE FOR .DYNAMOS.

SPECIFICATION forming part of Letters Patent No. 426,109, dated April 22, 1890.

Application filed December 30. 1889. Serial No. 335,299. (No model.)

T to whom it may concern: being broken. Its effect is to put the dynamo Be it known that I, ERNEST P. CLARK, a out of action the instant the line is broken, citizen of the United States, residing in New and to maintain it in this condition until set York city, in the county of New York and to work again manually. 5 State of New York, have invented certain new Its construction and method of operation and useful Improvements in Safety Devices are as follows:

for'Series-WVound Dynamos, of which the fol- A represents a series-wound dynamo, whose lowing is a specification. working-circuit, containing translating de- In operating series-wound dynamos, if the Vices, is represented by B. In the working- 1o line-wire is broken by accident or design, the circuit is also placed a magnet b, whoscarmaflow of current being interrupted, the electroture is attached to a pivoted latch-lever Z), as motive force falls to a greater or less degree, shown in Fig. 2. Vhen the magnet is de-endepending upon the power of the dynamo and ergized, a spring draws the end of the lever the residual magnetism of its field-magnet away from its pole. 6; I 5 cores. The electro-motive force which still 0 represents a pivoted switch-arm having exists may be sufficient in the case of large a handle for manual operation. A-spring c powerful dynamos to administer dangerous is attached to itin such a manner that its tendshocks to persons or animals that may acciency is to draw it over into contact with a dentally come in contact with the broken metallic terminal 0 the movement of the arm 20 wires. Should the broken wires, in falling, being limited by a stop-pin 0 The latchmake contact with any other good conductor lever 13 is adapted to engage with the arm 0 such as another wire, an awning-frame, or and hold it under the tension of spring 0 out metallic roofthis conductor becomes part of of contact with the terminal 0 and the latch the circuit, which being thus completed the is held in this engagement by the magnet l). 7 25 dynamo at once resumes its action,ren :lering The circuits which this device controls are the accidental portion of the circuit highly as follows: The levercis connected,as shown, dangerous to persons coming in contact with to the wire 1 proceeding from the last end of it, as well as being liable to cause fires by theiield-magnet coils. Theterminal c is conreason of the faulty nature of the contacts nected by wire 2 to the beginning of the field- 30 with the broken endsof wire. Another danger magnet coils. It is obvious then that when from such an accident is to the dynamo itself. the switch-arm is in contact with terminal 0 At the moment of interruption of the current a shunt of low resistance is established around the lamps or other translating devices at once the field-magnet coils. assume their condition of lowest resistance. Fig. 2 is a side view of the electro-magnet b 3 5 It, then, the circuit is suddenly closed, the and the latch Z), which it controls.

dynamo resumes its action instantly, and the In operation, therefore, when by accident or result is an abnormal rush of current, which otherwise the main circuit becomes broken may injure or destroy the dynamo. This is magnet b loses its power, and the latch Z) is particularly the case if an automatic regulapulled out of engagement with switch-arm c, o tor is used with the machine, such regula thus allowing it to be forced into contact with tors operating to maintain a constant current terminal c and to close the shunt-circuit through a variable resistance when, as in case around the field-magnet coils of the machine. of a broken line, the resistance becomes very The machine, therefore, becomes powerless great or infinite, the regulator in the eifort to immediately, and no part of the circuit is in 5 5 maintain the current will at once apply the a dangerous con.dition,nor can it be rendered greatest electro-motive force the machine can so until the switch-arm c has been restored to produce, thus increasing the dangers from the its normal running position. This device will broken wires. be placed at the generating-station, and when- 7 The object of myinvention to protect the ever the operator there notices the change in 50 dynamo from such accidents, as well as to the position of the switch he knows that a render the wires harmless in the event of their break has occurred. and takes steps to repair it. He is also careful not to put the switch into running condition again until the n eeessary repairs have been made. hen the machine is stopped, the switch is thrown in the same manner as by an accident, and it is therefore necessary to set the switch when the machine is started up again. This operation necessitates sufficient observation of the apparatus to know whetherit is in perfect working condition. It is to be observed that the switch-arm 0 might be placed directly in the main circuit with the magnet, in which case the operation of the switch by the magnet would be to effect a second break in the main circuit, which would remain open until again closed by hand. My preferred form, however, is that described herein in detail.

Having thus described my invention, I claim- A safety device for dynamo-electric inachines, consisting of a magnet in the lnit lll circuit, a shunt-circuit around the field-co ls of the machine, and a circuit-closer insaid shunt-circuit controlled by the said magnet, said circuit-closer consisting of a spring-operated switch-arm, a latch for holding the arm in its open position, said latch being operated by the magnet, and a terminal, into contact with which the arm is to be forced by the spring when it is released by the latch.

In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

ERNEST l. CLARK.

lVitnesses:

WM. A. RosENBAUM, .Lxnns ll. SEYMOUR. 

